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Name _______________________________ Final exam Geology 103 Spring, 2014 Short answer questions: 5 points each 1) Describe the sorting of these sedimentary environments: Beach Dune Glacial outwash Alluvial fan River 2) What name would you give to a sandstone that is 30% orthoclase, 30% plagioclase, 20% quartz, 10% plutonic rock fragments, and 10% mica? This sandstone is well-cemented, with 80% grains, traces of matrix, and up to 20% silica cement. Use Gilbert’s sandstone classification system. You do not need to draw the classification system! 3) List at least 5 physical or geochemical factors that are used to determine coal rank. 4) What is planar tabular cross bedding? Draw a block diagram that shows the bedding in three dimensions. 5) How do ball and pillow structures form? Draw a simple sketch of ball and pillow structures, and label the sediment types that are involved. 6) Are complete Bouma sequences common in the field? Why or why not? 7) What is the intersection point on an alluvial fan? Draw a simple sketch to illustrate. What large-scale factors control the position (or migration) of the intersection point? 2 8) What causes coral bleaching? 9) Describe the series of minerals that form as seawater evaporates. 10) Define the variables in the Reynolds equation: Re = V L What conditions might produce true laminar flow in nature? 3 11) List the differences between an meandering stream and a braided stream. Include these features: stream load, channel morphology (width/depth), sinuosity, braiding parameter, gradient, amount of floodplain material present, common bedforms and common sedimentary structures. (14 points). Meandering Braided Stream load Channel morphology (width/depth) Sinuosity Braiding parameter Gradient Amount of floodplain material present Common bedforms 12) Describe some of the distinctive features that are found in a beach environment. Include grain size, sorting, roundness, texture and sedimentary structures that would help you identify a beach deposit in the rock record. (6 points) Grain size: Sorting: Roundness: Surface texture: Bedding: Sedimentary structures: 4 13) Draw the following grain types in plain and cross-polarized light. List the optical properties of each grain type in plain and cross-polarized light. (12 points) Volcanic Rock Fragment (VRF) _ppl:_______________________ ___________________________ ___________________________ _xpl:_______________________ ___________________________ ___________________________ Plutonic Rock Fragment (PRF) _ppl:_______________________ ___________________________ ___________________________ _xpl:_______________________ ___________________________ ___________________________ Metamorphic rock fragment (MRF) _ppl:_______________________ ___________________________ ___________________________ _xpl:_______________________ ___________________________ ___________________________ 5 14) Name the sedimentary units that are exposed in the Sacramento area, from oldest to youngest. Begin with the Ione Formation. Give a very brief description of each, and focus on features that are distinctive for each unit. (8 points) 15) Describe the series of bedforms that occur as current velocity increases. Draw a simple sketch of each. Show where the change occurs from the lower flow regime to the upper flow regime. (10 points) 6